Flame-heater cathode tube



March 9, 1948. Q. J. wlcK FLAME-HEATER CATHODE TUBE Filed July 2, 1946 Fig 5" INVEN TOR.

inlay J Wm:

. flr/OP/VEYJ Patented Mar. 9, 1948 UNITED STATES PATENT QlFFl-CE 3 Claims.

This invention relates to thermionic tubes, and more particularly to an electron tube wherein thermionic emission is obtained by applying a flame to the cathode to raise it to operating temperature.

A main object of the invention is to provide a. novel and improved electron tube device of very simple construction wherein the customary cathode-heating filament is omitted and wherein the cathode is heated by a flame, no electrical power supply being required for heating the cathode.

A further object of the invention is to provide a thermionic tube wherein very high emission is obtained, said tube being relatively small in physical size, being inexpensive to manufacture and having beam characteristics whereby high power handling capability, high power sensitivity and high emciency are obtained.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a top plan view of a thermionic tube constructed in accordance with the present invention.

Figure 2 is an elevational view of the tube of Figure 1.

Figure 3 is a bottom plan view of the tube of Figure 1.

Figure 4 is an enlarged vertical cross-sectional view of the tube oi Figure 1.

Figure 5 is a horizontal cross-sectional view of the tube taken on line 5-5 of Figure 4.

Referring to the drawings, l designates a generally cylindrical metal housing or shell to which is secured an axial inner metal tubular member l2, which functions as the cathode of the tube. The space between cathode l2 and shell II is hermetically sealed by an annular bottom member i3 oi insulating material, said space being evacuated to a very low pressure. Positioned in said space coaxially with cathode I2 is a cylindrical plate to, and interposed between plate It and the cathode and coaxial therewith is a cylindrical grid l5. Grid I5 is connected to a contact prong l6 which passes through bottom member l3 and is secured thereto and plate It is connected to a similar contact prong IT. A flame device [8, such as a Bunsen burner, is adapted to be positioned inside cathode l2 to heat said cathode to the temperature required for the thermionic emission of electrons.

Cathode i2 is formed with a plurality of radial corrugations I! of substantial depth and extendin; parallel to the axis of the cathode for its en- "tire length. The inner crests of-saidcorrugations t9 define heat transmission fins which cathode 12 also emits electrons but at a lower density, the majority 01 the electrons being confined to the radial sheets above described. By thus corrugating the cathode, the active emission area is greatly increased, as over a. smoothly cylindrical cathode, and the current-handling capability of thetube is considerably magnified.

The flow of electrons from cathode i2 is modulated in the usual manner by signal voltage a plied to grid IS.

A further advantage derived from the corrugated cathode employed in the tube is that the inter-electrode capacitance between the cathode and the grid, and between the cathode and the plate is the same as or less than with the smoothly cylindrical cathode, whereas theelectron'emission of the corrugated cathode is much greater, as above explained. Sald emission will be rnunla;

greater than that obtained in. conventional tub es, l

having electrically heated cathodes since much greater heat may be applied to the cathode by the above-described flame method.

Since the cathode is heated by a flame directly applied thereto, no separate electrical power sup-- ply for heating the cathode is required.

Although the specific embodiment above de scribed is a triode, the present invention may be applied to any of the conventional tube. types employing more than one grid by substituting the flame-heated cathode for the electrically heated cathode employed in the tubes of the prior art.

While a specific embodiment of a flame-activated electron tube has been disclosed in the foregoing description it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore it is intended that no limitations be placed on the invention other than as defined by the scope of the appended claims.

What is claimed is:

1. An electron tube comprising an annular metal shell having a non-conducting portion. said shell being hermetically sealed and evacuated, an electrode in said shell, said electrode being spaced from the inner wall of the shell, and a terminal in said non-conducting portion connected to said electrode, said inner wall being corrugated.

2. An electron tube comprising an annular shell having a corrugated metal inner wall portion and a non-conducting outer wall portion, said shell being hermetically sealed and evacuated, an electrode in said shell, said electrode being spaced from said inner wall portion, and a terminal in said non-conducting portion connected to said electrode.

3. An electron tube comprising an annular metal shell which is generally cylindrical in external contour and having a non-conducting base, said shell being hermetically sealed and evacuated, a plurality oi spaced concentric cylindrical electrodes in said shell, the inner electrode being spaced from the inner wall of the shell, said inner wall being formed with a plurality of radial corrugations extending parallel to the axis 01' the shell and defining a plurality oi inwardly extending radial fins, in the hollow center of the shell, and a plurality of terminal prongs carried by said 4 base. each electrode being connected to a terminal prong.

QUINTIN J. WICK 5 REFERENCES CITED The following references are of record in the file of this patent:

. UNITED STATES PATENTS 10 Number Name Date 1,632,370 Bartlett t al. June 21, 1927 1,667,977 Lucian May 1, 1928 1,945,749 Moran Feb. 6, 1934 1,968,608 Lowry July 31, 1934 15 2,032,179 Lowry Feb. 25, 1936 2,048,129 Loughridge July 21, 1936 2,052,542 Thomas Aug. 25, 1936 FOREIGN PATENTS 20 Number Country Date 645,829 Germany June 4. 1937 

